Object of pressed or sprayed material fitted with a sign



Feb. 5, 1952 HL-CAPREZ ETAL 2,584,841

OBJECT 0F PRESSED OR SPRAYED MATERIAL FITTED WITH A SIGN Filed Feb 19 1945 N R w@%@ MST Haw B.

A TTOR/VE Y Patented Feb. 5, 1952 'ITED STATES f TENT OFFICE "OBJECTOF PRESSED OR. SPRAYED MATE- RIAL FITTED WITH A SIGN Application February 19, 1945, Serial N 0. 578,700 In Switzerland August 12, 1944 6' Claims.

According to the invention this drawback is overcome by the fact that at least the portion of the surface of the object carrying the sign is provided with a firmly adherent transparent coating which secures the signs against falling out.

The manufacturing process of theobject under consideration consists in that the object fitted with the sign is at first given at least one coating and then allowed to dry at least during hours at temperatures from 35 to 60 C.

The accompanying drawing illustrates a typewriter key as an example of embodiment of the invention, in' which a hardening substance of difierent colour from the body of the key and representing a sign has been brought into channels or grooves.

Fig. 1 shows a top view of the key, and

Fig. 2 represents a longitudinal section thereof along the line AA of Fig. 1. h

The given example is a key with the letter E (Fig 1), the shaping of the sign in the key being easily visible in Fig. 2.

The key button consists of a pressed or injected material which may be any of the thermoplastics or thermosets commonly used in injection or compression molding. In the present case an acetyl cellulose substance is utilized as spray or press material, of which the actual key body I is manufactured by the die-casting process. The key button 1 contains deepened channels la, lb, 10 and 1d. The character E designating the key is a plastic composition which fills, in the body of the key, channels corresponding to the character, and the plastic composition is injected under pressure. For rendering the sign conspicuous the filling material may, for instance, be in white colour, whereas the key body can, for instance, be of black material. The material of the letter E is likewise made of acetyl cellulose.

According to the invention the face of the key, 1. e. that portion of the surface on which the 2 sign or signs are visible, is provided with a firmly adherent and transparent coating 2 capable'oi preventing the sign from falling out.

In the present example thecoating 2 consists of a transparent lacquer whose base is identical with the material used for key button and sign, hence in the present case likewise of acetyl cellulose. The lacquer contains a solvent, so that due to the fact that the three substances. i. e. for key button, sign and lacquer, are synthesized on the same base, a partial dissolution of the keybutton surface is attained and consequently an intimate mixture of the lacquer both on the'surface of the key-button as well as on that of the sign is ensured.

The solvent for the lacquer coating comprises chiefly acetone, ordinaryalcohol or other organic solvents of high boilin points. The'pro'cess for producing the coating which secures the sign against falling out consists in the following essential working stages:

According to the present example, the key body fitted with the sign is, prior to applying thecoating, thoroughly dried at a temperature from 35 to 60 C. during about 16 to 20 hours. Subsequently the lacquer coating is produced on the key-button surface, preferably by means of a spray gun, whereupon the key is again allowed to dry for about 1 hour at 35 to 60 C. Then follows the spraying of another lacquer layer, after which the key is once more thoroughly dried'at temperatures between 35 and 60 C. during 16 to 20 hours.

At the end of these working stages there 'results a firmly adherent lacquer coating 2 both on the surface'of the key and on'the sign, being so intimately mixed with this surface that mechanically the coating isstrong enough to prevent a falling out of the sign E whether inserted or injected, even if in the long run the material should somewhat contract owing to various influences. The coating constitutes, moreover,- a protection against the access of moisture to the surface of. the key-button l and to'the sign E. Since the lacquer includes less softening media than the key and sign, especially that of the sign, a penetration of moisture is practically precluded. If, when spraying the sign, bubbles should arise between the channels and the filling substance, then the sign material working or expanding, for instance, at difierent temperatures is at any rate retained by the coating 2.

In many cases dull key-buttons are desired. With the process described hereinbefore a bright lacquer layer is obtained. Now, in order to get a coating embodying all the aforementioned features, by means of which, however, a dullness of the key face is attained, a solvent is added to the lacquer described so far which is capable of reducing the drying time and the viscosity of the lacquer. For the dullness there are two essential requirements, namely:

(1) Very fine lacquer spray,

(2) Rapid drying of the lacquer, in order that the tiny particles of the lacquer dry on before they run entirely into one another.

Therefore, in the present example, the solvent of the lacquer employed for obtaining dullness contains at least 60 per cent of acetone.

The process for producing a dull coating is as follows:

The ready-made key is, as described herein before, provided with a first lacquer layer. Then follows an over-spraying with the second lacquer which will be done in several only finely applied films. lhereby care is to be taken that, on the one hand, these layers dry so quickly that the single particles do not run entirely into one another, while on theother hand, the next layer will each time be applied only when the preceding one has dried. After having applied several such layers the key is allowed to dry for about 1 hour.

It is understood that according to the selection of viscosity and drying time, of the compressed air pressure in the spray gun and of the lacquer feeding, the surface can be made more or less dull.

The coating is at least as hard as the base material of the key or the sign, so that the coated key is largely protected against mechanical influences, such as, e. g. impinging finger nails.

Obviously, in the process of producing the coating there will always be treated a rather large number of objects or keys simultaneously. So it is readily possible to have 1000 keys sprayed at a time. The keys are arranged on hurdles, whereby the duration of the multi-layer spraying requires only a few minutes time. Since during the drying process of the keys put on the hurdles other hurdles with keys can be treated with the spraying apparatus, a continuous serial production of keys with such coatings is rendered possible.

While we have described a specific embodiment of our invention it is to be understood that the details of producing the object under review may be changed by those skilled in the art within the purview of this invention.

What we claim is:

1. The method of making a sign bearing element, which consists in forming a body of a synthetic plastic material having a sign defining channel in one of its faces, filling said channel with a similar plastic of different colorthan said body exposed at said face to form a sign distinctive in appearance from the body, said similar plastic at the time of filling being in the plastic state, and then coating said face of the body and exposed portions of the filling with a transparent coating liquid material of the same synthesis as the body and filling, and including an evaporative solvent acting in the hardening of the coating to integrate and bind particles of the body, filling and coating together.

2. The method of making a sign bearing element, which consists in forming a body of cellulosic material having a sign defining channel in one of its faces, filling said channel with a similar material in the plastic state to form a sign displayed on said face of the body, and then coating said face of the body and exposed portions of the filling with a cellulosic material including an evaporative solvent acting in the hardening of the coating to surface soften the body and filling and integrate and bind particles of the body, filling and coating together.

3. A sign bearing element comprising a body of a synthetic plastic material, a sign forming filling of an appearance distinctive from the body embedded in a channel in the body and exposed at one of its surfaces, said filling having been introduced in said body in the plastic state, and a coating consisting of layers of transparent material covering said surface and exposed portions of the filling.

4. The process of claim 2 in which the coated sign bearing element of cellulosic material is given at least one coating of cellulosic material afterwards allowed to dry at a temperature within the range of 35 C. to 60 C. for at least 15 hours.

5. The process of claim 2 in which the sign bearing element of cellulosic material is covered with several coatings of said cellulosic coating materials with intermediate drying of each of said several coatings.

6. The process of claim 2 in which the sign bearing element is coated with a plurality of layers of cellulose lacquer coating containing fine lacquer particles with intermediate drying so that the fine lacquer particles dry before entirely coalescing.

HANS CAPREZ. ERNST KRUSE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Switzerland Sept. 1, 1938 

